Self-Diffusion Coefficient of Liquid Magnesium near the Melting Temperature

Multicomponent aluminum-based alloys are important in various industries. The percentage of the base component with various impurities and alloying additions in such alloys plays a fundamental role in achieving the required properties of the final product. For our research, information on the diffusion properties of alloying components, such as Si, Cu, Mg, Sc, Ca, Ti, Zr, and Cr, in the liquid state is useful. Unfortunately, for these elements (except for Cu), even in the pure form, the required information in the literature is insufficient. In this work, the self-diffusion coefficient of liquid Mg is chosen as an object of study. The calculations are carried out, starting from the melting temperature at a step of 30 K, in the range 923–1043 K within the framework of an approach based on three theoretical components: the linear trajectory method, the model square-well potential, and the random phase approximation. The results obtained are comparable with all the data of a computer experiment available in the literature, although to a better extent with the result of classical MD. At the same time, the slight increase in our calculated values of the self-diffusion coefficient with temperature can point to their better agreement with ab initio MD results with a significant increase in temperature, which is due to an increase in the RPA accuracy with temperature. The study shows that, in the absence of experimental information on the self-diffusion coefficient of a liquid metal, the approach of joint use of the linear trajectory method, the square-well potential, and the random phase approximation can be a workable tool for estimating this property.